Michelle is enjoying a picnic across the valley from a cliff. She is playing music on her radio (assume it to be an isotropic source) and notices an echo from the cliff. She claps her hands and the echo takes 0.9 s to return.
(a) Given that the speed of sound in air is 343 m/s on that day, how far away is the cliff?
m
(b) If the intensity of the music 1.0 m from the radio is 1.0 10-5 W/m2, what is the intensity of the music arriving at the cliff?
W/m2